NAME
fma, fmaf, fmal - floating-point multiply and add SYNOPSIS
#include
double fma(double x, double y, double z); float fmaf(float x, float y, float z); long double fmal(long double x, long double y, long double z); Link with -lm. Feature Test Macro Requirements for glibc (see featuretestmacros(7)): fma(), fmaf(), fmal(): XOPENSOURCE >= 600 || ISOC99SOURCE || POSIXCSOURCE >= 200112L;
or cc -std=c99 DESCRIPTION The fma() function computes x * y + z. The result is rounded as one ternary operation according to the current rounding mode (see fenv(3)). RETURN VALUE These functions return the value of x * y + z, rounded as one ternary operation. If x or y is a NaN, a NaN is returned. If x times y is an exact infinity, and z is an infinity with the oppo‐ site sign, a domain error occurs, and a NaN is returned. If one of x or y is an infinity, the other is 0, and z is not a NaN, a domain error occurs, and a NaN is returned. If one of x or y is an infinity, and the other is 0, and z is a NaN, a domain error occurs, and a NaN is returned. If x times y is not an infinity times zero (or vice versa), and z is a NaN, a NaN is returned. If the result overflows, a range error occurs, and an infinity with the correct sign is returned. If the result underflows, a range error occurs, and a signed 0 is returned. ERRORS See matherror(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur: Domain error: x * y + z, or x * y is invalid and z is not a NaN
An invalid floating-point exception (FEINVALID) is raised. Range error: result overflow
An overflow floating-point exception (FEOVERFLOW) is raised. Range error: result underflow
An underflow floating-point exception (FEUNDERFLOW) is raised. These functions do not set errno. VERSIONS These functions first appeared in glibc in version 2.1. ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌──────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├──────────────────────┼───────────────┼─────────┤
│fma(), fmaf(), fmal() │ Thread safety │ MT-Safe │ └──────────────────────┴───────────────┴─────────┘ CONFORMING TO
C99, POSIX.1-2001. SEE ALSO remainder(3), remquo(3) COLOPHON
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2010-09-20 FMA(3)